idiom. Used to describe someone lacking both a shred of sanity and a smidgeon of testicular fortitude.
Real citation: "If you ask me, I find myself preferring the old Buffy-whipped Angelus. This new, improved one is not playing with a full sack."
(Spike, "Passions," Feb. 24, 1998, Buffy the Vampire Slayer)
Made-up citation: “The entire Democratic party is clearly not playing with a full sack, and they’re dumb as a challenged box of rocks to boot.”